don't they still make Z80s? I doubt you could still get a 286 or 386 new though
That would probably be one of your best hopes for building a computer today that's likely to have long-lived (in the sense of availability) parts even though it's probably not a drop-in 8088 replacement at the hardware level.
https://maker.pro/pic/projects/z80-computer-project-part-1-t...